Screening for highly active beta-lactam antibiotics against Agrobacterium tumefaciens.

Quantitative in vitro antibacterial activities, i.e., minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs), of 12 beta-lactam antibiotics against Agrobacterium tumefaciens strains LBA4404 and EHA101 were examined, in order to identify antibiotics effective in eliminating the bacteria in Agrobacterium-mediated plant genetic transformation. The antibacterial activities of beta-lactams tested against strain EHA101 were equal to or less than those tested against strain LBA4404. Cefotaxime, cefbuperazone, and meropenem had high activities against strain LBA4404 (MBC <1 mg l(-1)). Against strain EHA101, however, only meropenem showed activity comparable to that against strain LBA4404. The production of beta-lactamase was observed only in strain EHA101.